1. Field of the Invention
The present invention relates generally to the field of IP communication, and more particularly to a method for providing Internet Protocol (IP) telephony with quality of service (QoS) using end-to-end Resource Reservation Protocol (RSVP) signaling.
2. Discussion of the Related Art
The Internet community is working toward one day having all forms of inter-personal communication carried over the Internet. Video broadcasts, radio transmissions, computer data and telephone systems will merge into one medium and be transported anywhere in the world without any loss of perceived quality.
In order to be commercially practicable however, IP communications such as IP telephony and other IP communication services will require a quality of service (QoS) equal to or better than that currently available on digital circuit switched networks. This requires end-to-end QoS in corporate IP networks and across the IP backbones that carry traffic between the end networks. While QoS is available, it requires the usage of network resources and therefore, service providers will only ensure QoS if authorization and payments are supported across the domains where the communications are taking place.
Several protocols and services have been developed to handle the various aspects of IP communications. For instance, Session Initiation Protocol (SIP) was developed for call setup; Open Settlement Protocol (OSP) was developed for authorization and usage reporting and is used between policy servers and a clearing house for pricing, usage exchange and settlements for services; Common Outsourcing Policy Service (COPS) was developed for policy deployment in network elements and is used between the policy server and other network elements to communicate policy applicable for microflows that have QoS support; Resource Reservation Protocol (RSVP) was developed for setting up QoS in end networks and refers to a signaling protocol to request QoS from the network. RSVP is an end-to-end signaling protocol and can be used between corresponding telephony clients in the respective domains; Subnet Bandwidth Manager (SBM) was developed for setting up RSVP initiated QoS in 802.x style LANs; and Differentiated Services (DiffServ) was developed for setting up QoS traffic classes in IP backbones.
In order to complete a phone call on the Internet, at least three things should occur. First, the called party has to be alerted. Second, the connection between the callers must be established, and finally, resources to connect to callers may have to be set aside exclusively for the conversation. These steps do not have to occur in this order however. To this end, SIP is responsible for establishing the session while RSVP is responsible for reserving the resources necessary for a call.
Providing IP communications with QoS across the Internet requires a common way of usage for call setup, authorization, and QoS. Though the individual protocols above have been developed in detail, there is currently no reported method on how to use the individual protocols together in a consistent way across the Internet. In addition, there are no reported methods for dynamically establishing QoS policy for SIP-based voice and video calls on the Internet.